callback_lock grants the holder read-only access to cpusets.  For fixing
a synchronization issue between cpusets and scheduler core, it is now
required to make callback_lock available to core scheduler code.

Convert callback_lock to raw_spin_lock, so that it will be always safe
to acquire it from atomic context.

Signed-off-by: Juri Lelli <juri.le...@redhat.com>
---
 kernel/cgroup/cpuset.c | 66 +++++++++++++++++++++---------------------
 1 file changed, 33 insertions(+), 33 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 266f10cb7222..5b43f482fa0f 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -288,7 +288,7 @@ static struct cpuset top_cpuset = {
  */
 
 static DEFINE_MUTEX(cpuset_mutex);
-static DEFINE_SPINLOCK(callback_lock);
+static DEFINE_RAW_SPINLOCK(callback_lock);
 
 static struct workqueue_struct *cpuset_migrate_mm_wq;
 
@@ -922,9 +922,9 @@ static void update_cpumasks_hier(struct cpuset *cs, struct 
cpumask *new_cpus)
                        continue;
                rcu_read_unlock();
 
-               spin_lock_irq(&callback_lock);
+               raw_spin_lock_irq(&callback_lock);
                cpumask_copy(cp->effective_cpus, new_cpus);
-               spin_unlock_irq(&callback_lock);
+               raw_spin_unlock_irq(&callback_lock);
 
                WARN_ON(!is_in_v2_mode() &&
                        !cpumask_equal(cp->cpus_allowed, cp->effective_cpus));
@@ -989,9 +989,9 @@ static int update_cpumask(struct cpuset *cs, struct cpuset 
*trialcs,
        if (retval < 0)
                return retval;
 
-       spin_lock_irq(&callback_lock);
+       raw_spin_lock_irq(&callback_lock);
        cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
-       spin_unlock_irq(&callback_lock);
+       raw_spin_unlock_irq(&callback_lock);
 
        /* use trialcs->cpus_allowed as a temp variable */
        update_cpumasks_hier(cs, trialcs->cpus_allowed);
@@ -1175,9 +1175,9 @@ static void update_nodemasks_hier(struct cpuset *cs, 
nodemask_t *new_mems)
                        continue;
                rcu_read_unlock();
 
-               spin_lock_irq(&callback_lock);
+               raw_spin_lock_irq(&callback_lock);
                cp->effective_mems = *new_mems;
-               spin_unlock_irq(&callback_lock);
+               raw_spin_unlock_irq(&callback_lock);
 
                WARN_ON(!is_in_v2_mode() &&
                        !nodes_equal(cp->mems_allowed, cp->effective_mems));
@@ -1245,9 +1245,9 @@ static int update_nodemask(struct cpuset *cs, struct 
cpuset *trialcs,
        if (retval < 0)
                goto done;
 
-       spin_lock_irq(&callback_lock);
+       raw_spin_lock_irq(&callback_lock);
        cs->mems_allowed = trialcs->mems_allowed;
-       spin_unlock_irq(&callback_lock);
+       raw_spin_unlock_irq(&callback_lock);
 
        /* use trialcs->mems_allowed as a temp variable */
        update_nodemasks_hier(cs, &trialcs->mems_allowed);
@@ -1338,9 +1338,9 @@ static int update_flag(cpuset_flagbits_t bit, struct 
cpuset *cs,
        spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
                        || (is_spread_page(cs) != is_spread_page(trialcs)));
 
-       spin_lock_irq(&callback_lock);
+       raw_spin_lock_irq(&callback_lock);
        cs->flags = trialcs->flags;
-       spin_unlock_irq(&callback_lock);
+       raw_spin_unlock_irq(&callback_lock);
 
        if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
                rebuild_sched_domains_locked();
@@ -1755,7 +1755,7 @@ static int cpuset_common_seq_show(struct seq_file *sf, 
void *v)
        cpuset_filetype_t type = seq_cft(sf)->private;
        int ret = 0;
 
-       spin_lock_irq(&callback_lock);
+       raw_spin_lock_irq(&callback_lock);
 
        switch (type) {
        case FILE_CPULIST:
@@ -1774,7 +1774,7 @@ static int cpuset_common_seq_show(struct seq_file *sf, 
void *v)
                ret = -EINVAL;
        }
 
-       spin_unlock_irq(&callback_lock);
+       raw_spin_unlock_irq(&callback_lock);
        return ret;
 }
 
@@ -1989,12 +1989,12 @@ static int cpuset_css_online(struct cgroup_subsys_state 
*css)
 
        cpuset_inc();
 
-       spin_lock_irq(&callback_lock);
+       raw_spin_lock_irq(&callback_lock);
        if (is_in_v2_mode()) {
                cpumask_copy(cs->effective_cpus, parent->effective_cpus);
                cs->effective_mems = parent->effective_mems;
        }
-       spin_unlock_irq(&callback_lock);
+       raw_spin_unlock_irq(&callback_lock);
 
        if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
                goto out_unlock;
@@ -2021,12 +2021,12 @@ static int cpuset_css_online(struct cgroup_subsys_state 
*css)
        }
        rcu_read_unlock();
 
-       spin_lock_irq(&callback_lock);
+       raw_spin_lock_irq(&callback_lock);
        cs->mems_allowed = parent->mems_allowed;
        cs->effective_mems = parent->mems_allowed;
        cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
        cpumask_copy(cs->effective_cpus, parent->cpus_allowed);
-       spin_unlock_irq(&callback_lock);
+       raw_spin_unlock_irq(&callback_lock);
 out_unlock:
        mutex_unlock(&cpuset_mutex);
        return 0;
@@ -2065,7 +2065,7 @@ static void cpuset_css_free(struct cgroup_subsys_state 
*css)
 static void cpuset_bind(struct cgroup_subsys_state *root_css)
 {
        mutex_lock(&cpuset_mutex);
-       spin_lock_irq(&callback_lock);
+       raw_spin_lock_irq(&callback_lock);
 
        if (is_in_v2_mode()) {
                cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask);
@@ -2076,7 +2076,7 @@ static void cpuset_bind(struct cgroup_subsys_state 
*root_css)
                top_cpuset.mems_allowed = top_cpuset.effective_mems;
        }
 
-       spin_unlock_irq(&callback_lock);
+       raw_spin_unlock_irq(&callback_lock);
        mutex_unlock(&cpuset_mutex);
 }
 
@@ -2174,12 +2174,12 @@ hotplug_update_tasks_legacy(struct cpuset *cs,
 {
        bool is_empty;
 
-       spin_lock_irq(&callback_lock);
+       raw_spin_lock_irq(&callback_lock);
        cpumask_copy(cs->cpus_allowed, new_cpus);
        cpumask_copy(cs->effective_cpus, new_cpus);
        cs->mems_allowed = *new_mems;
        cs->effective_mems = *new_mems;
-       spin_unlock_irq(&callback_lock);
+       raw_spin_unlock_irq(&callback_lock);
 
        /*
         * Don't call update_tasks_cpumask() if the cpuset becomes empty,
@@ -2216,10 +2216,10 @@ hotplug_update_tasks(struct cpuset *cs,
        if (nodes_empty(*new_mems))
                *new_mems = parent_cs(cs)->effective_mems;
 
-       spin_lock_irq(&callback_lock);
+       raw_spin_lock_irq(&callback_lock);
        cpumask_copy(cs->effective_cpus, new_cpus);
        cs->effective_mems = *new_mems;
-       spin_unlock_irq(&callback_lock);
+       raw_spin_unlock_irq(&callback_lock);
 
        if (cpus_updated)
                update_tasks_cpumask(cs);
@@ -2312,21 +2312,21 @@ static void cpuset_hotplug_workfn(struct work_struct 
*work)
 
        /* synchronize cpus_allowed to cpu_active_mask */
        if (cpus_updated) {
-               spin_lock_irq(&callback_lock);
+               raw_spin_lock_irq(&callback_lock);
                if (!on_dfl)
                        cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
                cpumask_copy(top_cpuset.effective_cpus, &new_cpus);
-               spin_unlock_irq(&callback_lock);
+               raw_spin_unlock_irq(&callback_lock);
                /* we don't mess with cpumasks of tasks in top_cpuset */
        }
 
        /* synchronize mems_allowed to N_MEMORY */
        if (mems_updated) {
-               spin_lock_irq(&callback_lock);
+               raw_spin_lock_irq(&callback_lock);
                if (!on_dfl)
                        top_cpuset.mems_allowed = new_mems;
                top_cpuset.effective_mems = new_mems;
-               spin_unlock_irq(&callback_lock);
+               raw_spin_unlock_irq(&callback_lock);
                update_tasks_nodemask(&top_cpuset);
        }
 
@@ -2425,11 +2425,11 @@ void cpuset_cpus_allowed(struct task_struct *tsk, 
struct cpumask *pmask)
 {
        unsigned long flags;
 
-       spin_lock_irqsave(&callback_lock, flags);
+       raw_spin_lock_irqsave(&callback_lock, flags);
        rcu_read_lock();
        guarantee_online_cpus(task_cs(tsk), pmask);
        rcu_read_unlock();
-       spin_unlock_irqrestore(&callback_lock, flags);
+       raw_spin_unlock_irqrestore(&callback_lock, flags);
 }
 
 void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
@@ -2477,11 +2477,11 @@ nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
        nodemask_t mask;
        unsigned long flags;
 
-       spin_lock_irqsave(&callback_lock, flags);
+       raw_spin_lock_irqsave(&callback_lock, flags);
        rcu_read_lock();
        guarantee_online_mems(task_cs(tsk), &mask);
        rcu_read_unlock();
-       spin_unlock_irqrestore(&callback_lock, flags);
+       raw_spin_unlock_irqrestore(&callback_lock, flags);
 
        return mask;
 }
@@ -2573,14 +2573,14 @@ bool __cpuset_node_allowed(int node, gfp_t gfp_mask)
                return true;
 
        /* Not hardwall and node outside mems_allowed: scan up cpusets */
-       spin_lock_irqsave(&callback_lock, flags);
+       raw_spin_lock_irqsave(&callback_lock, flags);
 
        rcu_read_lock();
        cs = nearest_hardwall_ancestor(task_cs(current));
        allowed = node_isset(node, cs->mems_allowed);
        rcu_read_unlock();
 
-       spin_unlock_irqrestore(&callback_lock, flags);
+       raw_spin_unlock_irqrestore(&callback_lock, flags);
        return allowed;
 }
 
-- 
2.17.1

Reply via email to